unit 1: safety and dimensional analysis

Unit 1: Safety and Dimensional Analysis

1. Laboratory Safety……………….Slides 5-122. Dimensional Analysis………..Slides 13-23

Table of Contents

C.1.A demonstrate safe practices during laboratory and field investigations, including the appropriate use of safety showers, eyewash fountains, safety goggles, and fire extinguishers

C.1.B know specific hazards of chemical substances such as flammability, corrosiveness, and radioactivity as summarized on the Material Safety Data Sheets (MSDS)

C.2.E plan and implement investigative procedures, including asking questions, formulating testable hypotheses, and selecting equipment and technology, including graphing calculators, computers and probes, sufficient scientific glassware such as beakers, Erlenmeyer flasks, pipettes, graduated cylinders, volumetric flasks, safety goggles, and burettes, electronic balances, and an adequate supply of consumable Chemicals

C.2.F collect data and make measurements with accuracy and precision

C.2.G express and manipulate chemical quantities using scientific conventions and mathematical procedures, including dimensional analysis, scientific notation, and significant figures

Scientific Process SkillsEOC Standards

• Chemical Hazard Label• MSDS

LABORATORY SAFETY

NFPA CHEMICAL HAZARD LABEL

HEALTH

SPECIAL REACTIVITY(Stability)

FLAMMABILITYRED

BLUE YELLOW

WHITE

Health HazardDescribe effects of

chemical exposure to body, symptoms and what do in a medical

emergency.

Specific HazardDescribes any

important specific Hazard, such the

chemical it is most reactive with.

Fire HazardDescribes how

easily a chemical can catch fire.

Reactivity HazardDescribes how

unstable a chemical can be when in contact

with another chemical or

solution.

0LeastSerious

4Most

Serious

NFPA CHEMICAL RATINGS

1 04

40Flammable vapor which burns readily

Substance is stable

NFPA CHEMICAL HAZARD LABEL

Will not react when in contact

with other chemicals.

41 0

SASimple

Asphyxiant

Methane

Methane is nontoxic. It

can, however, reduce the amount of

oxygen in the air

necessary to support life.

Burns readily.

C. Johannesson

NFPA CHEMICAL HAZARD LABEL

Completed Label for Phosphine

Possible Required Personal Protective Equipment

Chemical Hazards and Precautions

MSDSMaterial Safety Data Sheet

On file for all purchased chemicals.

Includes all information shown on a chemical label and more.

Different formats are used by different chemical companies.

Dimensional Analysis

Dimensional analysis is a problem-solving method that uses the idea that any number or expression can be multiplied by one without changing its value.

Dimensional analysis is used to convert one unit of measurement to another unit of measurement using conversion factors.

These Conversion Factors are fixed and unchanging relationships.

I. What is Dimensional Analysis?

II. Useful Conversions factors:

III.How do you do Dimensional Analysis?

There are 5 Steps1. Start with what value is known,

proceed to the unknown.2. Draw the dimensional lines or fence (count the “jumps”).3. Insert the Conversion Factor.4. Cancel the units.5. Do the math, include units in answer.

IV. How do you set up a problem?Using conversion factors and the following set up

we can jump from unit to unit in a breeze!

Box #1Write the value that needs to be

converted.

Box # 3One side of the

Conversion factor

Box #2Write a “1” in the

denominator

Box # 4One side of the

Conversion factor (same unit as in

box #1)

V. Lets try Example #AHow many Slices there are in 7 Pizzas?

Given: 7 Pizzas Want: Slices

Conversion: 1 Pizza=8 Slices

SolutionCheck your work…

7 Pizzas

18 Slices1 Pizza

= 56

Slices

1

Now do the Math! Multiply and divide by denominator.

Conversion factor

Example B… How old are you in days?

Given: 17 yearsWant: # of days

Conversion: 365 days = one year

SolutionCheck your work…

17 Years

1365 Days1 Year =

6056 Days

1

Example C There are 2.54 cm in one inch.

How many inches are in 17.3 cm?

Given: 17.3 cmWant: # of inches

Conversion: 2.54 cm = one inch

SolutionCheck your work…

17.3 cm1

1 in2.54 cm

= 6.81 in

1